Liquid crystal solution, liquid crystal display device including liquid crystal solution and method of fabricating the same

ABSTRACT

A liquid crystal display device includes: a substrate; a thin film transistor in a pixel region over the substrate; a common electrode over the thin film transistor; a pixel electrode connected to the thin film transistor; and a liquid crystal layer including a plurality of liquid crystal capsules over the common electrode and the pixel electrode, wherein each of the plurality of liquid crystal capsules includes a shell and a core having a plurality of liquid crystal molecules therein, and wherein a gap distance between the liquid crystal molecules in adjacent liquid crystal capsules is equal to or greater than 20 nm and equal to or smaller than 0.3 times of a capsule diameter of the adjacent liquid crystal capsules.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional Application of U.S. application Ser.No. 15/582,135, filed on Apr. 28, 2017, which claims the benefit ofpriority of Korean Patent Application No. 10-2016-0052502 filed in theRepublic of Korea on Apr. 28, 2016, all of which are hereby incorporatedby reference in its entirety for all purposes as if fully set forthherein.

BACKGROUND OF THE INVENTION Field of the Invention

The present disclosure relates to a liquid crystal display device, andmore particularly to a liquid crystal display device including a liquidcrystal layer of a liquid crystal capsule and a method of fabricatingthe same.

Description of the Related Art

Recently, as the information age progresses, display devices processingand displaying a large amount of information have rapidly advanced. Forexample, various flat panel displays (FPDs) having a thin profile, alight weight and a low power consumption have been researched.

As a result, a thin film transistor liquid crystal display (TFT-LCD)having an excellent color reproducibility and a thin profile has beendeveloped. The LCD device displays an image using an optical anisotropyand a polarization property of a liquid crystal molecule.

The LCD device includes first and second substrates facing and spacedapart from each other and a liquid crystal layer between the first andsecond substrates. Since the LCD device includes two glass substrates, aweight and a thickness of the LCD device increases and it is not easy toapply the LCD device to a flexible display device.

To improve the above disadvantage, an LCD device including a liquidcrystal layer having liquid crystal capsules has been suggested. Theliquid crystal layer having the liquid crystal capsules may be formedthrough a coating method.

FIG. 1 is cross-sectional view showing a LCD device including a liquidcrystal capsule according to the related art. In FIG. 1, a related artLCD device 10 includes a substrate 20 and a liquid crystal layer 42 onthe substrate 20. The liquid crystal layer 42 includes a binder 44 andliquid crystal capsules 46 dispersed in the binder 44.

When a size (a diameter) of each of the liquid crystal capsules 46 issmaller than a wavelength of a visible ray, an optical change will notoccur such as a scattering due to a refractive index difference betweenthe binder 44 and the liquid crystal capsules 46. As a result, anoptical property such as a transmittance of the LCD device 10 isimproved.

When the liquid crystal capsules 46 are dispersed in the binder 44, aparticle agglomeration A of the liquid crystal capsules 46 may becaused. When a size of the liquid crystal capsules in the particleagglomeration A (an average diameter of the particle agglomeration A) isgreater than a wavelength of a visible ray, a scattering may occur.

Next, FIG. 2 is a view showing a scattering due to a particleagglomeration of a related art LCD device including a liquid crystalcapsule shown in FIG. 1. In FIG. 2, when a size of the liquid crystalcapsules 46 in the particle agglomeration A is greater than a wavelengthof a visible ray, a scattering occurs as a white spot B of the LCDdevice 10. Since a black level of the LCD device 10 increases due to thewhite spot B, a contrast ratio of the LCD device 10 is reduced.

FIG. 3 is a view showing a transmittance-voltage (TV) curve of a relatedart LCD device including a liquid crystal capsule shown in FIG. 1. InFIG. 3, the liquid crystal capsule 46 in the liquid crystal layer 42 ofthe LCD device 10 of a first sample s1 has a first shell thickness, andthe liquid crystal capsule 46 in the liquid crystal layer 42 of the LCDdevice 10 of a second sample s2 has a second shell thickness greaterthan the first shell thickness.

For the first sample s1, although a maximum transmittance of a whitelevel has an excellent value of about 90%, a minimum transmittance of ablack level increases to a value of about 5.1% due to the frequentparticle agglomeration A. For the second sample s2, although a minimumtransmittance of a black level has an excellent value of about 1.5% dueto the rare particle agglomeration, a maximum transmittance of a whitelevel decreases to a value of about 70%.

In the LCD device 10 including a liquid crystal capsule according to therelated art, since the liquid crystal capsules 46 are not uniformlydispersed in the binder 44, the particle agglomeration A occurs. Sincethe particle agglomeration A is expressed as the white spot B, the blacklevel increases and the contrast ratio is reduced.

Although a dispersion condition such as a surface modification of theliquid crystal capsule 46, the optimum binder 44 and the introduction ofan additive is required for improving the black level and the contrastratio, there exists a limit for obtaining the optimum dispersioncondition.

SUMMARY OF THE INVENTION

Accordingly, the present disclosure is directed to an LCD deviceincluding a liquid crystal capsule and a method of fabricating the samethat substantially obviate one or more of problems due to limitationsand disadvantages of the prior art.

In accordance with the present disclosure, as embodied and broadlydescribed herein, the present disclosure provides a liquid crystal layerincluding a binder; and a plurality of liquid crystal capsules dispersedin the binder, wherein each of the plurality of liquid crystal capsulesincludes a shell and a core having a plurality of liquid crystalmolecules therein, and wherein a gap distance between the liquid crystalmolecules in adjacent liquid crystal capsules is equal to or greaterthan 20 nm and equal to or smaller than 0.3 times of a capsule diameterof the adjacent liquid crystal capsules.

In another aspect, the present disclosure provides a liquid crystaldisplay device including: a substrate; a thin film transistor in a pixelregion over the substrate; a common electrode over the thin filmtransistor; a pixel electrode connected to the thin film transistor; anda liquid crystal layer including a plurality of liquid crystal capsulesover the common electrode and the pixel electrode, wherein each of theplurality of liquid crystal capsules includes a shell and a core havinga plurality of liquid crystal molecules therein, and wherein a gapdistance between the liquid crystal molecules in adjacent liquid crystalcapsules is equal to or greater than 20 nm and equal to or smaller than0.3 times of a capsule diameter of the adjacent liquid crystal capsules.

In another aspect, the present disclosure provides a method offabricating a liquid crystal display device including: forming a thinfilm transistor in a pixel region on a substrate; forming a commonelectrode over the substrate; forming a pixel electrode connected to thethin film transistor; and forming a liquid crystal layer including aplurality of liquid crystal capsules over the common electrode and thepixel electrode, wherein each of the plurality of liquid crystalcapsules includes a shell and a core having a plurality of liquidcrystal molecules therein, and wherein a gap distance between the liquidcrystal molecules in adjacent liquid crystal capsules is equal to orgreater than 20 nm and equal to or smaller than 0.3 times of a capsulediameter of the adjacent liquid crystal capsules.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the embodiments as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this specification, illustrate embodiments and together with thedescription serve to explain the principles of the disclosure. In thedrawings:

FIG. 1 is cross-sectional view showing a related art LCD deviceincluding a liquid crystal capsule.

FIG. 2 is a view showing a scattering due to a particle agglomeration ofthe related art LCD device including a liquid crystal capsule shown inFIG. 1.

FIG. 3 is a view showing a transmittance-voltage (TV) curve of therelated art LCD device including a liquid crystal capsule shown in FIG.1.

FIGS. 4A and 4B are cross-sectional views showing a black state and awhite state, respectively, of an LCD device including a liquid crystalcapsule according to an embodiment of the present disclosure.

FIG. 5 is a flowchart illustrating a method of fabrication of the liquidcrystal layer according to an embodiment of the present disclosure.

FIG. 6 is a view showing a liquid crystal layer of an LCD deviceincluding a liquid crystal capsule according to an embodiment of thepresent disclosure.

FIGS. 7A and 7B are views showing a transmittance-voltage (TV) curve ofan LCD device including a liquid crystal capsule according to anembodiment of the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the present disclosure, examplesof which are illustrated in the accompanying drawings. In particular,FIGS. 4A and 4B are cross-sectional views showing a black state and awhite state, respectively, of an LCD device including a liquid crystalcapsule according to an embodiment of the present disclosure.

In FIGS. 4A and 4B, a LCD device 110 includes a substrate 120 where athin film transistor (TFT) T, a common electrode 134 and a pixelelectrode 138, and a liquid crystal layer 142 are formed. A gateelectrode 122 is formed in each pixel region P on the substrate 120, anda gate insulating layer 124 is formed on a whole of the gate electrode122 over the substrate 120. In addition, a semiconductor 126 is formedon the gate insulating layer 124 corresponding to the gate electrode122, and a source electrode 128 and a drain electrode 130 are formed onboth end portions of the semiconductor layer 126. The gate electrode122, the semiconductor layer 126, the source electrode 128 and the drainelectrode 130 constitute the TFT T.

Further, a gate line and a data line are formed on the substrate 120 andthe TFT T is connected to the gate line and the data line. The gate lineand the data line cross to define the pixel region P. Also, aninterlayer insulating layer 132 is formed on a whole of the TFT T overthe substrate 120, and the common electrode 134 is formed in the pixelregion P on the interlayer insulating layer 132. For example, the commonelectrode 134 may be disposed to be spaced apart from a portion directlyon the TFT T or may be disposed to be spaced apart from the portiondirectly on the TFT T and to partially overlap the TFT T.

In addition, a passivation layer 136 is formed on a whole of the commonelectrode 134 over the substrate 120, and the pixel electrode 138 isformed in the pixel region P on the passivation layer 136. Theinterlayer insulating layer 132 and the passivation layer 136 include adrain contact hole exposing the drain electrode 130, and the pixelelectrode 138 is connected to the drain electrode 130 through the draincontact hole. The common electrode 134 may have a plate shape, and thepixel electrode 138 may have a shape of a bars spaced apart from eachother or may have a plate shape including slits.

Although the pixel electrode 138 is formed on the common electrode 134in the embodiment of FIGS. 4A and 4B, the common electrode may be formedon the pixel electrode in another embodiment. In another embodiment, thepixel electrode may have a plate shape, and the common electrode mayhave a shape of bars spaced apart from each other or may have plateshape including slits. In another embodiment, the common electrode andthe pixel electrode each having a shape of bars may be formed as thesame layer or as the different layers.

Further, a color filter layer may be formed under the TFT T, between theTFT T and the common electrode 134 or between the TFT T and the pixelelectrode 138. The liquid crystal layer 142 is formed on the pixelelectrode 138, and includes a binder 144 and liquid crystal capsules 146dispersed in the binder 144, and each of the liquid crystal capsules 146includes liquid crystal molecules 148.

For example, the liquid crystal layer 142 may have a thickness of about2.5 μm to about 3.5 μm. In addition, the binder 144 may be transparentor translucent, and the binder 144 may be formed of a water solublematerial, a fat soluble material or a mixed material of the watersoluble material and the fat soluble material.

Further, each of the liquid crystal capsules 146 may be a polymercapsule having a diameter of about 1 nm to a value smaller than awavelength of a visible ray. For example, each of the liquid crystalcapsules 146 may include a water soluble material such as poly vinylalcohol (PVA) or a fat soluble material such as poly methyl methacrylate(PMMA).

The liquid crystal molecules 148 may include at least one of a nematicliquid crystal molecule, a ferroelectric liquid crystal molecule and aflexo electric liquid crystal molecule. For example, a capsule diameterof each of the liquid crystal capsules 146 may be within a range ofabout 1 nm to about 320 nm, and a volume ratio of the liquid crystalcapsules 146 to the liquid crystal layer 142 may be within a range ofabout 50% to about 80%. A refractive index anisotropy of each of theliquid crystal molecules 148 may be within a range of about 0.18 toabout 0.30, and a dielectric anisotropy of each of the liquid crystalmolecules 148 may be within a range of about 35 to about 100. Inaddition, as shown, a first polarizing plate 150 is formed under thesubstrate 120, and a second polarizing plate 152 is formed on the liquidcrystal layer 142.

Next, FIG. 5 is a flowchart illustrating a method of fabrication of theliquid crystal layer according to an embodiment of the presentdisclosure. In fabricating the liquid crystal display device 110, theliquid crystal layer 142 including the liquid crystal capsules 146 maybe formed as a film type through a coating method. The liquid crystalcapsules 146 may be formed using one of a coacervation method, anin-situ polymerization method, an interfacial polymerization method anda solvent evaporation method. For example, the fat soluble liquidcrystal capsule 146 may include poly methyl methacrylate (PMMA) formedthrough an interfacial polymerization method, and the water solubleliquid crystal capsule 146 may include poly vinyl alcohol (PVA) formedthrough a coacervation method. Specifically, in 5501, the polymer liquidcrystal capsule 146 including the liquid crystal molecule 148 thereinmay be formed by mixing the liquid crystal molecules 148 and a monomerand, in 5502, polymerizing the monomer and the liquid crystal molecules148 through the interfacial polymerization to form a liquid crystalsolution. In 5503, a liquid crystal capsule material layer is formed ona base film having the second polarizing plate 152 by coating the liquidcrystal solution including the liquid crystal capsules 146 through anozzle. In 5504, the liquid crystal capsule material layer is dried orcured to form the liquid crystal layer 142 of a film type.

In addition, after the base film having the liquid crystal layer 142 andthe second polarizing plate 152 is attached to the substrate having theTFT T, the common electrode 134 and the pixel electrode 138 using anadhesive layer or an adhesive, the base film is removed to complete theLCD device 110. Since the liquid crystal layer 142 is formed through asoluble process, the LCD device 110 is formed of the single substrate120. As a result, a thickness and a weight of the LCD device 110 arereduced. Also, since the binder 144 and the liquid crystal capsules 146are made using water soluble and/or fat soluble materials, the liquidcrystal layer is made of materials that are resistant to moisture.

In a black state of FIG. 4A, a voltage is not applied (OFF) between thecommon electrode 134 and the pixel electrode 138, and the liquid crystalmolecules 148 in each of the liquid crystal capsules 146 are randomlyarranged. While a light through the first polarizing plate 150 passesthrough the liquid crystal layer 142, a polarization state of the lightis not changed. As a result, the light is completely absorbed by thesecond polarizing plate 152 and the LCD device 110 displays a black.

In a white state of FIG. 4B, a voltage V is applied (ON) between thecommon electrode 134 and the pixel electrode 138, the liquid crystalmolecules 148 in each of the liquid crystal capsules 146 are arrangedalong an electric field generated between the common electrode 134 andthe pixel electrode 138. While a light through the first polarizingplate 150 passes through the liquid crystal layer 142, a polarizationstate of the light is changed. As a result, the light passes through thesecond polarizing plate 152 and the LCD device 110 displays a white.

In the liquid crystal layer 142, when a material of the binder 144 isdifferent from a material of the liquid crystal capsule 146, the shellthickness is of the liquid crystal capsule 146 may be determined by avolume ratio of the liquid crystal molecules 148 and the monomer.Accordingly, a gap distance g between the liquid crystal molecules 148in the adjacent liquid crystal capsules 146 may be determined by avolume ratio of the monomer mixed with the liquid crystal molecules 148and the liquid crystal molecules 148. For example, the liquid crystalcapsule 146 may be formed of a water soluble material while the binder144 may be made of a fat soluble material. When a material of the binder144 is the same as a material of the liquid crystal capsule 146, a gapdistance g between the cores 162 in the adjacent liquid crystal capsules146 may be determined by a volume ratio of the material of the binder144 and the liquid crystal molecules 148.

When some of the liquid crystal capsules 146 dispersed in the binder 144are agglomerated, two liquid crystal capsules 146 are disposed tocontact each other. As a result, the liquid crystal capsules 146 in theadjacent two liquid crystal capsules 146 are spaced apart from eachother by the gap distance g which is twice of the shell thickness ts ofthe liquid crystal capsule 146.

Accordingly, when the shell thickness ts of the liquid crystal capsule146 is formed to be equal to or greater than a half (½) of a minimum gapdistance gmin for preventing the particle agglomeration by adjusting thevolume ratio of the liquid crystal molecules 148 and the monomer or whenthe gap distance g between the cores 162 in the adjacent liquid crystalcapsules 146 is formed to be equal to or greater than the minimum gapdistance gmin by adjusting the volume ratio of the binder and the liquidcrystal molecules 148, a scattering due to a refractive index differencebetween the binder 144 and the liquid crystal capsule 146 is preventedeven in case of occurrence of the particle agglomeration by anon-uniform dispersion. As a result, a white spot and a black levelincrease are prevented and a reduction in a contrast ratio is prevented.

The prevention of the scattering due to the adjustment of the shellthickness ts of the liquid crystal capsule 146 will be illustratedhereinafter. In particular, FIG. 6 is a view showing a liquid crystallayer of the LCD device including a liquid crystal capsule in FIG. 4.

In FIG. 6, the liquid crystal layer 142 of the LCD device 110 includesthe binder 144 and the liquid crystal capsules 146 dispersed in thebinder 144. Each of the liquid crystal capsules 146 includes a shell 160and a core 162 where the liquid crystal molecules 148 (of FIGS. 4A and4B) are disposed. The shell includes one of poly vinyl alcohol (PVA) andpoly methyl methacrylate (PMMA). In addition, each of the liquid crystalcapsules 146 has a capsule diameter ds, a shell thickness ts and a corediameter dc, and the capsule diameter ds may be assumed to be a sum oftwice of the shell thickness ts and the core diameter dc (ds=2ts+dc).

A gap distance g between the liquid crystal molecules 148 in theadjacent liquid crystal capsules 146 may be expressed as a distancebetween the cores 162 of the adjacent liquid crystal capsules 146. Whentwo liquid crystal capsules 146 contact each other due to the particleagglomeration, the liquid crystal molecules 148 in the two liquidcrystal capsules 146 are spaced apart from each other by a minimum gapdistance gmin, and the minimum gap distance gmin is the same as twice ofthe shell thickness ts (gmin=2ts).

Accordingly, in the LCD device 110 including the liquid crystal capsuleaccording to the embodiment of the present disclosure, the minimum gapdistance gmin between the liquid crystal molecules 148 can be controlledby adjusting the shell thickness ts of the liquid crystal capsule 146 orthe gap distance g between the cores 162 in the adjacent liquid crystalcapsules 146. As a result, the black level of the LCD device 110 isreduced and the contrast ratio of the LCD device 110 increases bypreventing the scattering and the white spot.

Further, since the scattering is prevented even when the two liquidcrystal capsules 146 contact each other due to the particleagglomeration, a density of the liquid crystal capsule 146 in the liquidcrystal layer 142 is maximized, and a transmittance of the liquidcrystal layer 142 increases.

In addition, a range of the shell thickness ts of the liquid crystalcapsule 146 or a range of the gap distance g between the liquid crystalmolecules 148 in the adjacent liquid crystal capsules 146 can bedetermined by the minimum gap distance gmin and a volume ratio of theliquid crystal molecules 148 to the liquid crystal layer 142.

TABLE 1 shows a relation of a liquid crystal layer, a liquid crystalcapsule and a liquid crystal molecule of a LCD device including a liquidcrystal capsule according to an embodiment of the present disclosure.

TABLE 1 liquid crystal capsule shell core liquid crystal volume ratio indiam- thick- diam- volume ratio in liquid crystal eter(nm) ness(nm)eter(nm) capsule(%) layer(%) 50 5 40 51.2 34.8 10 30 21.6 14.7 15 20 6.44.4 100 5 90 72.9 49.6 10 80 51.2 34.8 15 70 34.3 23.3 20 60 21.6 14.730 40 6.4 4.4 40 20 0.8 0.5 150 5 140 81.3 55.3 10 130 65.1 44.3 15 12051.2 34.8 20 110 39.4 26.8 30 90 21.6 14.7 40 70 10.2 6.9 50 50 3.7 2.5200 5 190 85.7 58.3 10 180 72.9 49.6 15 170 61.4 41.8 20 160 51.2 34.830 140 34.3 23.3 40 120 21.6 14.7 50 100 12.5 8.5

In TABLE 1, when the capsule diameter ds of the liquid crystal capsule146 is about 50 nm, about 100 nm, about 150 nm and about 200 nm, thevolume ratio of the liquid crystal molecules 148 with respect to theliquid crystal layer 142 (a liquid crystal volume ratio in a liquidcrystal layer) can be controlled by adjusting the shell thickness ts,the core diameter dc, the volume ratio of the liquid crystal molecules148 with respect to the liquid crystal capsule 146 (a liquid crystalvolume ratio in a capsule) and the volume ratio of the liquid crystalcapsule 146 with respect to the liquid crystal layer 142.

Since the scattering is prevented even when two liquid crystal capsules146 contact each other due to the particle agglomeration, the volumeratio of the liquid crystal capsule 146 with respect to the liquidcrystal layer 142 may reflect about 68% of a packing density of a bodycentered cubic (BCC).

When the minimum gap distance gmin between the liquid crystal molecules148 for preventing the scattering is determined as about 20 nm, theshell thickness ts of the liquid crystal capsule 146 may be formed to beequal to or greater than about 10 nm, or the gap distance g between theliquid crystal molecules 148 in the liquid crystal capsule 146 may beformed to be equal to or greater than about 20 nm. As a result, thescattering and the white spot are prevented, the black level of theminimum transmittance is reduced, and the contrast ratio increases.

When the LCD device 110 has the white level of the maximum transmittanceequal to or greater than about 80%, a reduction in a display quality ofan image may be prevented. When the liquid crystal volume ratio in theliquid crystal layer is equal to or greater than about 20%, the whitelevel equal to or greater than about 80% may be obtained.

As a result, for improving the black level and the contrast ratio of theLCD device 110, the shell thickness ts of the liquid crystal capsule 146is formed to be equal to or greater than about 10 nm, or the gapdistance g between the liquid crystal molecules 148 in the adjacentliquid crystal capsules 146 is formed to be equal to or greater thanabout 20 nm. In addition, for improving the transmittance and thedisplay quality of the LCD device 110, the liquid crystal volume ratioin the liquid crystal layer is formed to be equal to or greater thanabout 20%.

Here, the liquid crystal volume ratio of the liquid crystal layer may bedetermined by the capsule diameter ds, the shell thickness ts, the corediameter dc and the liquid crystal volume ratio in the capsule.

Accordingly, a lower limit of the shell thickness ts of the liquidcrystal capsule 146 may be determined as about 10 nm based on animprovement of the black level and the contrast ratio, and an upperlimit of the shell thickness ts of the liquid crystal capsule 146 may bedetermined as about 0.15 times ( 3/20) of the capsule diameter ds basedon an improvement of the transmittance and the display quality.

Alternatively, a lower limit of the gap distance g between the liquidcrystal molecules 148 in the adjacent liquid crystal capsules 146 may bedetermined as about 20 nm based on an improvement of the black level andthe contrast ratio, and an upper limit of the gap distance g between theliquid crystal molecules 148 in the adjacent liquid crystal capsules 146may be determined as about 0.3 times ( 3/10) of the capsule diameter dsbased on an improvement of the transmittance and the display quality.

For example, when the capsule diameter ds of the liquid crystal capsule146 is about 50 nm, the liquid crystal volume ratio in the liquidcrystal layer is equal to or greater than about 20% in case of the shellthickness ts of about 5 nm. As a result, for the improvement of theblack level, the contrast ratio, the transmittance and the displayquality, the shell thickness ts may be determined within a range equalto or smaller than about 5 nm of about 0.1 times ( 1/10) of the capsulediameter ds, or the gap distance g between the liquid crystal molecules148 in the adjacent liquid crystal capsules 146 may be determined withina range equal to or smaller than about 10 nm of about 0.2 times (⅕) ofthe capsule diameter ds.

When the capsule diameter ds of the liquid crystal capsule 146 is about100 nm, the liquid crystal volume ratio in the liquid crystal layer isequal to or greater than about 20% in case of the shell thickness ts ofabout 5 nm, about 10 nm and about 15 nm. As a result, for theimprovement of the black level, the contrast ratio, the transmittanceand the display quality, the shell thickness ts may be determined withina range equal to or greater than about 10 nm and equal to or smallerthan about 15 nm of about 0.15 times ( 3/20) of the capsule diameter ds,or the gap distance g between the liquid crystal molecules 148 in theadjacent liquid crystal capsules 146 may be determined within a rangeequal to or smaller than about 20 nm of about 0.3 times ( 3/10) of thecapsule diameter ds.

When the capsule diameter ds of the liquid crystal capsule 146 is about150 nm, the liquid crystal volume ratio in the liquid crystal layer isequal to or greater than about 20% in case of the shell thickness ts ofabout 5 nm, about 10 nm, about 15 nm and about 20 nm. As a result, forthe improvement of the black level, the contrast ratio, thetransmittance and the display quality, the shell thickness ts may bedetermined within a range equal to or greater than about 10 nm and equalto or smaller than about 20 nm of about 0.13 times ( 2/15) of thecapsule diameter ds, or the gap distance g between the liquid crystalmolecules 148 in the adjacent liquid crystal capsules 146 may bedetermined within a range equal to or smaller than about 40 nm of about0.26 times ( 4/15) of the capsule diameter ds.

When the capsule diameter ds of the liquid crystal capsule 146 is about200 nm, the liquid crystal volume ratio in the liquid crystal layer isequal to or greater than about 20% in case of the shell thickness ts ofabout 5 nm, about 10 nm, about 15 nm, about 20 nm and about 30 nm. As aresult, for the improvement of the black level, the contrast ratio, thetransmittance and the display quality, the shell thickness ts may bedetermined within a range equal to or greater than about 10 nm and equalto or smaller than about 30 nm of about 0.15 times ( 3/20) of thecapsule diameter ds, or the gap distance g between the liquid crystalmolecules 148 in the adjacent liquid crystal capsules 146 may bedetermined within a range equal to or smaller than about 60 nm of about0.3 times ( 3/10) of the capsule diameter ds.

Accordingly, in the LCD device 110 including the liquid crystal capsuleaccording to the embodiment of the present disclosure, the shellthickness ts of the liquid crystal capsule 146 can be formed within arange equal to or greater than about 10 nm and equal to or smaller thanabout 0.15 times ( 3/20) of the capsule diameter ds, or the gap distanceg between the liquid crystal molecules 148 in the adjacent liquidcrystal capsules 146 can be formed within a range equal to or greaterthan about 20 nm and equal to or smaller than about 0.3 times ( 3/10) ofthe capsule diameter ds. As a result, the black level and the contrastratio are improved and the transmittance and the display quality areimproved.

When the shell thickness ts is smaller than about 10 nm or the gapdistance g between the liquid crystal molecules 148 in the adjacentliquid crystal capsules 146 is smaller than about 20 nm, the black levelincreases and the contrast ratio decreases due to the scattering. Whenthe shell thickness ts is greater than about 0.15 times ( 3/20) of thecapsule diameter ds or the gap distance g between the liquid crystalmolecules 148 in the adjacent liquid crystal capsules 146 is greaterthan about 0.3 times ( 3/10) of the capsule diameter ds, thetransmittance decreases and the display quality is deteriorated due to adeficiency of the liquid crystal molecule.

For example, the capsule diameter ds can be formed within a range ofabout 50 nm to about 200 nm. Further, the shell thickness ts can beformed within a range of about 10 nm to about 30 nm, or the gap distancebetween the liquid crystal molecules 148 in the adjacent liquid crystalcapsules 146 can be formed within a range of about 20 nm to about 60 nm.The liquid crystal volume ratio in the liquid crystal layer can beformed within a range of about 20% to about 50%.

The relation of the transmittance and the voltage of the LCD device 110according to the embodiment will be illustrated hereinafter. Inparticular, FIGS. 7A and 7B are views showing a transmittance-voltage(TV) curve of an LCD device including a liquid crystal capsule accordingto an embodiment of the present disclosure.

In the LCD device 110 of a first sample of FIG. 7A, a thickness of theliquid crystal layer 142 is about 3.1 μm, and the liquid crystal capsule146 is formed of poly vinyl alcohol (PVA). The shell thickness ts of theliquid crystal capsule 146 is within a range of about 10 nm to about 15nm, or the gap distance g between the liquid crystal molecules 148 inthe adjacent liquid crystal capsules 146 is within a range of about 20nm to about 30 nm. The capsule diameter ds of the liquid crystal capsule146 is within a range of about 100 nm to about 200 nm, and a volumeratio of the liquid crystal molecule 148 with respect to the liquidcrystal layer 142 is about 37%. Since the LCD device 110 of the firstsample has the excellent white level of a maximum transmittance of about80% and the excellent black level of a minimum transmittance of about0.29%, the black level and the contrast ratio are improved and thetransmittance and the display quality are improved.

In the LCD device 110 of a second sample of FIG. 7B, a thickness of theliquid crystal layer 142 is about 3.2 μm, and the liquid crystal capsule146 is formed of poly methyl methacrylate (PMMA). The shell thickness isof the liquid crystal capsule 146 is within a range of about 10 nm toabout 20 nm, or the gap distance g between the liquid crystal molecules148 in the adjacent liquid crystal capsules 146 is within a range ofabout 20 nm to about 40 nm. The capsule diameter ds of the liquidcrystal capsule 146 is within a range of about 100 nm to about 200 nm,and a volume ratio of the liquid crystal molecules 148 with respect tothe liquid crystal layer 142 is about 32%. Since the LCD device 110 ofthe second sample has the excellent white level of a maximumtransmittance of about 85% and the excellent black level of a minimumtransmittance of about 0.4%, the black level and the contrast ratio areimproved and the transmittance and the display quality are improved.

Consequently, in the LCD device including the liquid crystal capsuleaccording to the embodiment of the present disclosure, since the shellthickness of the liquid crystal capsule is formed within a range equalto or greater than about the half (½) of the minimum gap distance forpreventing the scattering and equal to or smaller than about 0.15 times( 3/10) of the capsule diameter for preventing the decrease of thetransmittance, or the gap distance between the liquid crystal moleculesin the adjacent liquid crystal capsules is formed within a range equalto or greater than the minimum gap distance for preventing thescattering and equal to smaller than about 0.3 ( 3/10) of the capsulediameter for preventing the decrease of the transmittance. As a result,the black level is reduced and the contrast ratio increases bypreventing the particle agglomeration and the white spot regardless ofthe dispersion degree of the liquid crystal capsule. Further, since thescattering is prevented even in case of the particle agglomeration, thedensity of the liquid crystal capsule is maximized and the displayquality is improved.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in a LCD device including aliquid crystal capsule and a method of fabricating the same of thepresent disclosure without departing from the sprit or scope of thedisclosure. Thus, it is intended that the present disclosure covers themodifications and variations of these aspects provided they come withinthe scope of the appended claims and their equivalents.

What is claimed is:
 1. A liquid crystal display device, comprising: asubstrate; a thin film transistor in a pixel region over the substrate;a common electrode over the thin film transistor; a pixel electrodeconnected to the thin film transistor; and a liquid crystal layerincluding a plurality of liquid crystal capsules over the commonelectrode and the pixel electrode, wherein the plurality of liquidcrystal capsules includes at least one pair of liquid crystal capsulesin direct contact with each other, wherein each of the plurality ofliquid crystal capsules includes a shell and a core having a pluralityof liquid crystal molecules therein, wherein a gap distance between theliquid crystal molecules in adjacent liquid crystal capsules is equal toor greater than 20 nm and equal to or smaller than 0.3 times of acapsule diameter of the adjacent liquid crystal capsules, wherein ashell thickness of each liquid crystal capsule among the at least onepair of liquid crystal capsules is equal to or greater than 10 nm andequal to or smaller than 0.15 times of a capsule diameter of each liquidcrystal capsule among the at least one pair of liquid crystal capsules,and wherein a volume ratio of the plurality of liquid crystal moleculeswith respect to the liquid crystal layer is within a range of 20% to50%.
 2. The display device of claim 1, wherein the gap distance betweenthe liquid crystal molecules in the adjacent liquid crystal capsules isequal to or smaller than 60 nm, and the shell thickness of the shell isequal to or smaller than 30 nm.
 3. The display device of claim 1,wherein the gap distance between the liquid crystal molecules in theadjacent liquid crystal capsules is determined by one of a volume ratioof a binder surrounding the plurality of liquid crystal capsules and theplurality of liquid crystal molecules and a volume ratio of a monomerand the plurality of liquid crystal molecules.
 4. The display device ofclaim 1, wherein the capsule diameter is within a range of 50 nm to 200nm.
 5. The display device of claim 1, wherein the shell includes one ofpoly vinyl alcohol (PVA) and poly methyl methacrylate (PMMA).
 6. Thedisplay device of claim 1, wherein a binder surrounding the plurality ofliquid crystal capsules includes one of a water soluble material, a fatsoluble material and a mixed material of the water soluble material andthe fat soluble material, and the binder has one of a transparency and atranslucence.
 7. The display device of claim 1, wherein the shellthickness of each liquid crystal capsule among the at least one pair ofliquid crystal capsules is within a range equal to or greater than 10 nmand equal to or smaller than 15 nm when the capsule diameter of eachliquid crystal capsule among the at least one pair of liquid crystalcapsules is 100 nm, wherein the shell thickness of each liquid crystalcapsule among the at least one pair of liquid crystal capsules is withina range equal to or greater than 10 nm and equal to or smaller than 20nm when the capsule diameter of each liquid crystal capsule among the atleast one pair of liquid crystal capsules is 150 nm, and wherein theshell thickness of each liquid crystal capsule among the at least onepair of liquid crystal capsules is within a range equal to or greaterthan 10 nm and equal to or smaller than 30 nm when the capsule diameterof each liquid crystal capsule among the at least one pair of liquidcrystal capsules is 200 nm.
 8. The display device of claim 1, whereinthe liquid crystal display device has a peak transmittance that flattensbetween 20 volts and 30 volts, and decreases by at least 1% or more from30 volts to 50 volts.
 9. A method of fabricating a liquid crystaldisplay device, comprising: forming a thin film transistor in a pixelregion on a substrate; forming a common electrode over the substrate;forming a pixel electrode connected to the thin film transistor; andforming a liquid crystal layer including a plurality of liquid crystalcapsules over the common electrode and the pixel electrode, wherein theplurality of liquid crystal capsules includes at least one pair ofliquid crystal capsules in direct contact with each other, wherein eachof the plurality of liquid crystal capsules includes a shell and a corehaving a plurality of liquid crystal molecules therein, wherein a gapdistance between the liquid crystal molecules in adjacent liquid crystalcapsules is equal to or greater than 20 nm and equal to or smaller than0.3 times of a capsule diameter of the adjacent liquid crystal capsules,wherein a shell thickness of each liquid crystal capsule among the atleast one pair of liquid crystal capsules is equal to or greater than 10nm and equal to or smaller than 0.15 times of a capsule diameter of eachliquid crystal capsule among the at least one pair of liquid crystalcapsules, and wherein a volume ratio of the plurality of liquid crystalmolecules with respect to the liquid crystal layer is within a range of20% to 50%.
 10. The method of claim 9, wherein forming the liquidcrystal layer comprises: mixing a monomer with the plurality of liquidcrystal molecules; forming a liquid crystal solution including theplurality of liquid crystal capsules by polymerizing the monomer and theplurality of liquid crystal molecules; forming a liquid crystal capsulematerial layer by coating the liquid crystal solution on a base film;and curing the liquid crystal capsule material layer.
 11. The method ofclaim 10, wherein the gap distance between the liquid crystal moleculesin the adjacent liquid crystal capsules is determined by one of a volumeratio of a binder surrounding the plurality of liquid crystal capsulesand the plurality of liquid crystal molecules and a volume ratio of themonomer and the plurality of liquid crystal molecules.
 12. The method ofclaim 9, wherein the shell includes one of poly vinyl alcohol (PVA) andpoly methyl methacrylate (PMMA).
 13. The method of claim 9, wherein theshell thickness of each liquid crystal capsule among the at least onepair of liquid crystal capsules is within a range equal to or greaterthan 10 nm and equal to or smaller than 15 nm when the capsule diameterof each liquid crystal capsule among the at least one pair of liquidcrystal capsules is 100 nm, wherein the shell thickness of each liquidcrystal capsule among the at least one pair of liquid crystal capsulesis within a range equal to or greater than 10 nm and equal to or smallerthan 20 nm when the capsule diameter of each liquid crystal capsuleamong the at least one pair of liquid crystal capsules is 150 nm, andwherein the shell thickness of each liquid crystal capsule among the atleast one pair of liquid crystal capsules is within a range equal to orgreater than 10 nm and equal to or smaller than 30 nm when the capsulediameter of each liquid crystal capsule among the at least one pair ofliquid crystal capsules is 200 nm.
 14. The method of claim 9, whereinthe liquid crystal display device has a peak transmittance that flattensbetween 20 volts and 30 volts, and decreases by at least 1% or more from30 volts to 50 volts.